Various forms of heat exchange tanks for containing CO.sub.2 snow heretofore have been provided and are adapted for removable placement in vehicle load bed bodies and other shipping containers of the closed type for maintaining the interiors of those bodies and containers chilled. Customarily, thermostatically controlled fans are provided for circulating the air within the closed bodies across the cooled external surfaces of the heat exchange tanks responsive to the temperature within the bodies rising above a predetermined maximum.
Most previously used heat exchange tanks of this type include interior header pipes equipped with one or more discharge nozzles for forming snow into the tanks as a result of liquid CO.sub.2 being supplied to the header pipes under pressure. Also, it is pointed out that the time required to fill such a heat exchange tank with CO.sub.2 snow varies according to the number of discharge nozzles and the effective size of the discharge nozzles.
Usually, a smaller cross sectional discharge nozzle or jet outlet opening will result in the production of a greater amount of CO.sub.2 snow for a given amount of liquid CO.sub.2 used. In some instances the users of heat exchange tanks of this type have personnel available and a savings in time required to fill a heat exchange tank with CO.sub.2 snow is not important. However, if personnel for this purpose are not readily available and the driver of the associated vehicle or some other personnel are required to fill a plurality of heat exchange tanks with CO.sub.2 snow, a savings in time becomes quite important.
Most previously known forms of heat exchange tanks include interior header pipes mounted within the tanks in a manner such that quick removal thereof is not possible. Accordingly, if it is desired to modify a heat exchange tank to include larger discharge jet apertures or nozzles to allow more rapid filling of the tanks with CO.sub.2 snow (even though this results in less snow being formed per pound of liquid CO.sub.2) considerable time must be spent in removing, modifying and reinstalling the header pipes or manifolds to enable short tank filling times.
Inasmuch as some tanks are rented and may be used during alternate weeks for customers who wish to use a slower economical fill rate and those who wish to use a faster less economical fill rate, a need exists for a heat exchange tank including a header or manifold pipe which may be quickly removed, modified and reinstalled.